Bottom Line:
Unbalanced tumor necrosis factor (TNF)-α production is associated with pathogenesis of a variety of human diseases.We demonstrated that NF-κB bound to DICER promoter and transcriptionally regulated DICER expression.Furthermore, we showed that the hepatocyte-specific depletion of Dicer in mice resulted in TNF-α overproduction and sensitized the mice to endotoxin, which could be corrected by administration of miR-125b mimics.

ABSTRACTUnbalanced tumor necrosis factor (TNF)-α production is associated with pathogenesis of a variety of human diseases. However, the molecular pathways maintaining TNF-α homeostasis remain elusive. Here, we report that NF-κB/p65-DICER-miRs axis negatively regulates TNF-α production. We demonstrated that NF-κB bound to DICER promoter and transcriptionally regulated DICER expression. In addition, the NF-κB/DICER signaling suppresses TNF-α expression by generating mature forms of miR-125b and miR-130a which negatively regulate TNF-α mRNA. Furthermore, we showed that the hepatocyte-specific depletion of Dicer in mice resulted in TNF-α overproduction and sensitized the mice to endotoxin, which could be corrected by administration of miR-125b mimics. These data suggest that NF-κB/p65-DICER-miRs axis involved in maintaining of TNF-α homeostasis, and injection of miR-125b as a potential therapeutic method for septic shock.

Figure 6: Knock down of DICER greatly sensitized mice to septic shock. Survival of DicerF/FAlbCre (A) or DicerF/FMx1Cre (B) mice injected intraperitoneally with saline or Infliximab (30μg/g, mAb or 90μg/g, 3mAb) 1 h before application of LPS was monitored over a period of 8 days (n=15-19). *P<0.05 vs DicerF/F. (C) Survival of DicerF/FAlbCre mice injected intravenously (i.v.) via lateral tail veins with nonsense (N.S.) or miR-125b mimics (1.5μg/g)12h before application of LPS was monitored over a period of 8 days (n=8-9). *P<0.05 vs N.S.. (D)A model depicting NF-κB-DICER-miRs regulatory circuitry in hepatic TNF-α expression. NF-κB activation induced TNF-α expression and also directed the expression of DICER and miRs to prevent overproduction of TNF-α.

Mentions:
We then examined the mouse survival after injection with a lethal dose LPS. Eight days after injection, more than 50% of the DicerF/F mice still remained alive, whereas only 26% DicerF/FAlbCre mice survived the challenge (Figure 6A). Further, administration of infliximab, the anti-TNF-α antibody known to block the action of TNF-α 39, significantly protected both the DicerF/FAlbCre and DicerF/F mice from LPS-induced toxicity. Remarkably, while all of the DicerF/FMx1Cre mice succumbed to LPS 36h after the challenge, 30% of the mice survived when infliximab was given (Figure 6B). Moreover, injection of miR-125b mimics could similarly prevent mice from LPS-induced toxicity (Figure 6C). These results suggested that the higher mortality rates of the Dicer mutant mice were mainly caused by the systemic effects of hepatic TNF-α overproduction.

Figure 6: Knock down of DICER greatly sensitized mice to septic shock. Survival of DicerF/FAlbCre (A) or DicerF/FMx1Cre (B) mice injected intraperitoneally with saline or Infliximab (30μg/g, mAb or 90μg/g, 3mAb) 1 h before application of LPS was monitored over a period of 8 days (n=15-19). *P<0.05 vs DicerF/F. (C) Survival of DicerF/FAlbCre mice injected intravenously (i.v.) via lateral tail veins with nonsense (N.S.) or miR-125b mimics (1.5μg/g)12h before application of LPS was monitored over a period of 8 days (n=8-9). *P<0.05 vs N.S.. (D)A model depicting NF-κB-DICER-miRs regulatory circuitry in hepatic TNF-α expression. NF-κB activation induced TNF-α expression and also directed the expression of DICER and miRs to prevent overproduction of TNF-α.

Mentions:
We then examined the mouse survival after injection with a lethal dose LPS. Eight days after injection, more than 50% of the DicerF/F mice still remained alive, whereas only 26% DicerF/FAlbCre mice survived the challenge (Figure 6A). Further, administration of infliximab, the anti-TNF-α antibody known to block the action of TNF-α 39, significantly protected both the DicerF/FAlbCre and DicerF/F mice from LPS-induced toxicity. Remarkably, while all of the DicerF/FMx1Cre mice succumbed to LPS 36h after the challenge, 30% of the mice survived when infliximab was given (Figure 6B). Moreover, injection of miR-125b mimics could similarly prevent mice from LPS-induced toxicity (Figure 6C). These results suggested that the higher mortality rates of the Dicer mutant mice were mainly caused by the systemic effects of hepatic TNF-α overproduction.

Bottom Line:
Unbalanced tumor necrosis factor (TNF)-α production is associated with pathogenesis of a variety of human diseases.We demonstrated that NF-κB bound to DICER promoter and transcriptionally regulated DICER expression.Furthermore, we showed that the hepatocyte-specific depletion of Dicer in mice resulted in TNF-α overproduction and sensitized the mice to endotoxin, which could be corrected by administration of miR-125b mimics.

ABSTRACTUnbalanced tumor necrosis factor (TNF)-α production is associated with pathogenesis of a variety of human diseases. However, the molecular pathways maintaining TNF-α homeostasis remain elusive. Here, we report that NF-κB/p65-DICER-miRs axis negatively regulates TNF-α production. We demonstrated that NF-κB bound to DICER promoter and transcriptionally regulated DICER expression. In addition, the NF-κB/DICER signaling suppresses TNF-α expression by generating mature forms of miR-125b and miR-130a which negatively regulate TNF-α mRNA. Furthermore, we showed that the hepatocyte-specific depletion of Dicer in mice resulted in TNF-α overproduction and sensitized the mice to endotoxin, which could be corrected by administration of miR-125b mimics. These data suggest that NF-κB/p65-DICER-miRs axis involved in maintaining of TNF-α homeostasis, and injection of miR-125b as a potential therapeutic method for septic shock.